The present invention claims the benefit of Korean Patent Application No. 2001-28119, filed in Korea on May 22, 2001, which is hereby incorporated by reference.
1. Field of the Invention
The present invention relates to a liquid crystal display (LCD) device, and more particularly, to a transflective LCD device for a mobile communication system, using a dispensing method.
2. Description of the Related Art
In general, a liquid crystal display (LCD) device has a first substrate that includes a thin film transistor (TFT), a second substrate that includes a color filter layer, and a liquid crystal material layer interposed therebetween. Fabrication of a liquid crystal cell of the LCD device includes formation of a common electrode and a pixel electrode on opposing surfaces of the first and second substrates, respectively, and the liquid crystal material is injected through an injection hole between the first and second substrates. A polarizing plate is attached on an outer surface of each of the first and second substrates to complete the liquid crystal cell. Accordingly, image data is displayed by the LCD device by adjusting a voltage that is applied to the common and pixel electrodes to control transmittance of the liquid crystal cell.
The complete process for fabricating the liquid crystal cell includes a limited number of individual steps. In contrast, fabrication processes for forming the TFT on the first substrate and forming the color filter layer on the second substrate may be classified into a significant number of individual fabrication steps. The individual fabrication steps include processes of forming an orientation film, forming a cell gap, injecting liquid crystal material into the cell gap, and forming individual liquid crystal cells. The process for injecting liquid crystal material is performed through one of a dip method or a contact method. In the dip method, the bonded first and second substrates are dipped into a vessel containing the liquid crystal material, and a pressure difference between the bonded first and second substrates and the vessel causes injection of the liquid crystal material into the cell gap through the injection hole. In the contact method, the injection hole contacts a surface of the liquid crystal material in the vessel, and a pressure difference between the bonded first and second substrates and the vessel causes injection of the liquid crystal material into the cell gap through the injection hole. Both the dip method and the contact method are time consuming and may cause contamination of the injection hole, thereby deteriorating display quality of the LCD device.
To solve the above problems, a dispensing method is suggested wherein a sealant is printed along a boundary of an array substrate that includes a plurality of individual liquid crystal cells. Then, the liquid crystal material is dropped within a region defined by the sealant using a dispenser. Accordingly, processing time is reduced and a production yield is dramatically improved.
FIGS. 1A to 1C are plan views showing a fabricating process of a liquid crystal cell using a dispensing method according to the related art, and FIGS. 1D to 1F are cross-sectional views of the fabrication process shown in FIGS. 1A to 1C according to the related art, respectively.
In FIGS. 1A and 1D, a first substrate 2 includes a plurality of unit cells xe2x80x9cAxe2x80x9d and a second substrate 4 (in FIGS. 1B and 1E) includes an array line (not shown), a pixel electrode (not shown), and a switching device (not shown). A sub-color filter layer (not shown) that corresponds to the pixel electrode and a black matrix (not shown) that corresponds to a space between the pixel electrodes are formed on the first substrate 2.
In FIGS. 1B and 1E, a sealant 6 is printed on the second substrate 4 corresponding to a boundary of the plurality of unit cells xe2x80x9cA.xe2x80x9d A liquid crystal material 8 (in FIG. 1E) is dropped on an inner region of the sealant 6 using a dispenser, and the first substrate 2 is attached to the second substrate 4 to form a LCD panel 10 (in FIG. 1F).
In FIGS. 1C and 1F, a photo mask 12 (in FIG. 1F) includes a transmissive portion xe2x80x9cBxe2x80x9d and a blocking portion xe2x80x9cCxe2x80x9d that are disposed over the LCD panel 10 (in FIG. 1F) for hardening of the sealant 6 by exposure to ultraviolet (UV) light. The transmissive portion xe2x80x9cBxe2x80x9d corresponds to a position of the sealant 6 of the LCD panel 10, and the blocking portion xe2x80x9cCxe2x80x9d correspond to an interior position xe2x80x9cDxe2x80x9d of each of the unit cells xe2x80x9cAxe2x80x9d (in FIG. 1C). The interior xe2x80x9cDxe2x80x9d of each of the unit cells xe2x80x9cAxe2x80x9d provides a mask to prevent a channel region of the TFT on the second substrate 4 from being exposed to the ultraviolet light during the hardening of the sealant 6. Then, the first and second substrates 2 and 4 are fully attached through a subsequent hot press process. Finally, the attached substrates are cut (diced) into individual unit cells xe2x80x9cA.xe2x80x9d
FIG. 2 is a plan view showing a second substrate of a unit cell according to the related art. In FIG. 2, a second substrate 20 includes a display portion xe2x80x9cExe2x80x9d and a surrounding portion xe2x80x9cF.xe2x80x9d A plurality of array lines (not shown), a plurality of switching devices (not shown), and a plurality of pixel electrodes (not shown) are formed within the display portion xe2x80x9cE.xe2x80x9d A pad portion xe2x80x9cJxe2x80x9d is formed to extend from the plurality of array lines at the surrounding portion xe2x80x9cF.xe2x80x9d The pad portion xe2x80x9cJxe2x80x9d is formed within a region that will be covered with a case of a mobile communication system.
FIG. 3 is a magnified plan view of partial regions xe2x80x9cGxe2x80x9d, xe2x80x9cH,xe2x80x9d and xe2x80x9cIxe2x80x9d of FIG. 2 according to the related art. In FIG. 3, a second substrate 20 includes a gate line 26 and a data line 28. The gate line 26 includes a gate pad 24 formed within a specific area at one end of the gate line 26. The gate line 26 crosses the data line 28 at a crossing point with an insulating layer (not shown) interposed therebetween, thereby defining a pixel region xe2x80x9cP.xe2x80x9d The data line 28 includes a data pad 30 formed within a specific area at one end of the data line 28. In general, the gate pads 24 and the data pad 30 are disposed within the surrounding portion xe2x80x9cFxe2x80x9d of the second substrate 20, and an external signal is applied to the gate pad 24 and the data pad 30. A TFT xe2x80x9cTxe2x80x9d includes a gate electrode 32, an active layer 34 formed on the gate electrode 32, and a source electrode 36 and a drain electrode 38 formed on both ends of the active layer 34. The TFT xe2x80x9cTxe2x80x9d is disposed adjacent to the crossing point of the gate line 26 and the data line 28. A transflective electrode 40 is formed on the pixel region xe2x80x9cPxe2x80x9d and is connected to the drain electrode 38 for applying the external signal that drives a liquid crystal layer (not shown). The transflective electrode 40 defines a reflective portion xe2x80x9cKxe2x80x9d and a transmissive portion xe2x80x9cL,xe2x80x9d and includes a reflective electrode 40a having a transmissive hole 42 and a transmissive electrode 40b formed over or under the reflective electrode 40a with an insulating layer (not shown) interposed therebetween. A sealant (not shown) is formed at the surrounding portion xe2x80x9cFxe2x80x9d (of FIG. 2) of the array substrate 20.
FIG. 4 is a cross-sectional view taken along IVxe2x80x94IV of FIG. 3 according to the related art, and FIG. 5 is a cross-sectional view taken along Vxe2x80x94V of FIG. 3 according to the related art. In FIG. 4, an LCD panel xe2x80x9cMxe2x80x9d for a mobile communication system 50 includes an attached array substrate 20 and a color filter substrate 52, and a liquid crystal material layer 48 disposed therebetween. The LCD panel xe2x80x9cMxe2x80x9d may be classified into a display portion xe2x80x9cExe2x80x9d and a surrounding portion xe2x80x9cF.xe2x80x9d A backlight 54 is disposed under the LCD panel xe2x80x9cMxe2x80x9d and is used for a transmissive mode of the LCD panel xe2x80x9cM.xe2x80x9d A case 56 covers the backlight 54 and the surrounding portion xe2x80x9cFxe2x80x9d of the LCD panel xe2x80x9cMxe2x80x9d in FIG. 5.
As shown in FIG. 5, an LCD device fabricated using the dispensing method, a black matrix 58 should not be formed within a region where the sealant 46 is formed. Accordingly, a width of the black matrix 58 at the surrounding portion xe2x80x9cExe2x80x9d (in FIG. 4) is about one-half of a width for an LCD device fabricated using the injecting method.
FIG. 6 is a cross-sectional view illustrating a relationship between widths of a black matrix and a sealant according to the related art. In FIG. 6, a width of a surrounding portion is 2.8 mm and a width of a black matrix 58 is reduced to an amount xe2x80x9cxcex1xe2x80x9d that is about one-half of a width of a black matrix for a LCD device fabricated by the injecting method. The black matrix 58 is spaced apart from a sealant 46 by an amount xe2x80x9cxcex21.xe2x80x9d For the sealant having a width of xe2x80x9cxcex3,xe2x80x9d since the sealant 46 is formed at a portion spaced apart from an edge of a mobile communication system by an amount xe2x80x9cxcex22,xe2x80x9d the surrounding portion of the mobile communication system is designed to have a width of xe2x80x9cxcex1+xcex21+xcex22+xcex3.xe2x80x9d
However, as shown in FIG. 5, a light leakage phenomenon may occur in a mobile communication system having a structure according to the related art because light 60 of the backlight 54 under the LCD panel xe2x80x9cMxe2x80x9d (in FIG. 4) is emitted at a vicinity xe2x80x9cS1xe2x80x9d of the case 56 through a space xe2x80x9cNxe2x80x9d between the sealant 46 at the surrounding portion xe2x80x9cFxe2x80x9d of the LCD panel xe2x80x9cMxe2x80x9d (in FIG. 4) and the black matrix 58. Therefore, a display quality of an LCD device according to the related art is deteriorated due to a difference in intensity at the surrounding portion of the LCD panel for the mobile communication system 50. In order to decrease a size of the mobile communication system while maintaining a sufficient liquid crystal display area, an area of the display portion of the LCD panel should be kept constant and an area of the surrounding portion of the LCD panel should be reduced. Accordingly, an area of the black matrix is also reduced, thereby subjecting the mobile communication system to a light leakage phenomenon.
Accordingly, the present invention is directed to a liquid crystal display device that substantially obviates one or more of the problems due to limitations and disadvantages of the related art.
An object of the present invention is to provide a compact and high quality mobile communication system by reducing a light leakage phenomenon at a surrounding portion of an LCD panel.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, an array substrate for a transflective liquid crystal display device includes a substrate having a display portion and a surrounding portion, a gate line on the substrate, a gate insulating layer covering the gate line, a data line on the gate insulating layer, a gate pad and a data pad within the surrounding portion, the gate pad connected to the gate line and the data pad connected to the data line, a switching device connected to the gate and data lines, a reflective electrode within the display portion and connected to the switching device, a reflective plate within the surrounding portion, a passivation layer on the reflective electrode and the reflective plate, and a transmissive electrode on the passivation layer and connected to the reflective electrode.
In another aspect, a fabricating method of an array substrate for a transflective liquid crystal display device includes forming a gate line on a substrate having a display portion and a surrounding portion, forming a gate insulating layer covering the gate line, forming a data line on the gate insulating layer, forming a gate pad and a data pad within the surrounding portion, the gate pad connected to the gate line and the data pad connected to the data line, forming a switching device connected to the gate and data lines, forming a reflective electrode within the display portion and connected to the switching device, forming a reflective plate within the surrounding portion, forming a passivation layer on the reflective electrode and the reflective plate, and forming a transmissive electrode on the passivation layer and connected to the reflective electrode.
In another aspect, a mobile communication system includes a transflective liquid crystal display panel having a display portion and a surrounding portion including a reflective plate, a backlight unit adjacent to the transflective liquid crystal panel, and a case enveloping the surrounding portion and the backlight unit.
In another aspect, a fabricating method for forming a mobile communication system includes forming a transflective liquid crystal display panel having a display portion and a surrounding portion including a reflective plate, forming a backlight unit adjacent to the transflective liquid crystal panel, and forming a case enveloping the surrounding portion and the backlight unit.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.